Low Three-Phase Voltage Alert
This feature is based on the
Trip on Three-Phase Voltage
element but is not a protection
element and will not lead to any IntelliRupter fault interrupter action. Instead, it notifies
the user via the
Operation
screen and a SCADA message that a low-voltage condition
exists on three phases. There is no SCADA-acknowledge functionality. The DNP point
will be active when voltage is below the alert setting for approximately one second. The
DNP point clears when voltage is above the threshold. To avoid flooding the logs and
creating a flurry of SCADA alerts when the voltage hovers at the threshold level, the DNP
point is not allowed more than one transition (on or off) per minute. (Setting options:
Yes
or
No
; default =
No
)
Low Three-Phase Low Voltage Threshold
This is the percentage of line-to-ground RMS phase voltage below which a
Three-Phase
Voltage Alert
state occurs. (Range: 5-100; Step: 1; Default: 75)
Figure 50. The
Setup>Protection>General Profile 1>Voltage, Frequency, and Sectionalizing>
Frequency Trip
screen.
Under Frequency Enabled
Specify the
Yes
or
No
(default) option.
Under Frequency Threshold
This is the frequency (in hertz) below which a
Trip
operation will occur. Enter between
47 and 60 Hz, but the setting is valid only if it falls within the range (System Frequency - 3,
System Frequency). (Minimum: System Frequency - 3 Hz; Maximum: System Frequency;
Default: System Frequency - 0.5 Hz; Increment: 0.02)
Over Frequency Enabled
Specify the
Yes
or
No
(default) option.
Frequency Trip Section
Each
General Profile
feature has settings for multiple
Frequency Trip
elements. See
Figure 50.
Frequency Trip
S&C Instruction Sheet 766-530 83
Protection Setup